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You know that there are twenty… (Class 12 Biology 2024, Q5)

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BiologyCBSE Class 12 · Board exam 2024, set 57/1/1 · 1 mark · MCQ

CBSE Class 12 Biology 2024: question 5

Set in the CBSE Class 12 board exam of 2024, paper 57/1/1, section A, question 5, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q5 · 1 mark · MCQCompetency-basedMolecular Basis of Inheritance

You know that there are twenty different types of naturally occurring amino acids and four different types of bases in the DNA. A combination of 3 such bases code for a specific amino acid. If instead there are 96 different amino acids and 12 different bases in the DNA, then the minimum number of combination of bases required to form a codon is :

  1. (A)6
  2. (B)8
  3. (C)2
  4. (D)4

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 57/1/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

With 4 bases, triplets give codons.

Hint 2

Find the smallest n for which is at least 96.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. With 12 different bases, a codon of n bases gives combinations. For n = 1 this is 12, which is less than 96. For n = 2 it is 144, which is at least 96.

    1 mark

  2. Therefore the minimum codon length is 2 bases.

Answer: (C) 2

Where the marks are

  • Uses to get n = 2 (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Molecular Basis of Inheritance, one at a time, marked against the answer key and marking points.Back to the full paper2024 board paper, set 57/1/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.